1. Field of the Invention
The present invention relates to a visual and audio system for theaters, and more particularly to a visual and audio system for theaters which can achieve a remarkable improvement in brightness, visual presence, and resolution, while extending the field of visual presence to the entire screen area, and allowing viewers to experience a sound effect coming directly from the screen.
2. Description of the Related Art
Conventional visual and audio systems for theaters include a projector, a planar screen, and an audio system installed behind the planer screen.
Referring to FIG. 11, a conventional stereoscopic visual and audio system is illustrated. As shown in FIG. 11, the conventional stereoscopic visual and audio system includes a pair of projectors 2, polarizers 4 symmetrically arranged at the front of projection lenses respectively attached in the projectors 2 while defining a certain angle therebetween, and a planar screen 11. Viewers can view stereoscopic images from the projectors 2 projected onto the planer screen 11 through polarizing glasses 4 having a desired polarization degree.
The transmissivity of each polarizer 4 is 50% at maximum, and typically on the level of 40%. Accordingly, only 40% of the light emerging from the projector is transmitted through each polarizer 4, and then reached onto the planar screen 11. Also, only 40% of the resultant light is transmitted through the viewer""s polarizing glasses 5. Finally, the viewer can see very dark screen images with only 16-25% brightness of the projected light.
Although it is possible to view stereoscopic images under the condition in which both the right and left images have a high brightness, this has not been accomplished due to the above-mentioned degraded brightness.
For this reason, many efforts to enhance the screen brightness for showing stereoscopic images have been made.
Referring to FIG. 1, a typical shooting procedure is illustrated. As shown in FIG. 1, the image of the object 6 is recorded through a shooting lens 7 on the film 10 or other image recording medium.
The object 6 is a three-dimensional one having substantial volume. But the three-dimensional image is recorded forcefully on the planar film surface 10 as a flat image which is obtained from a designed shooting angle, based on the reflecting of the shooting lens 7.
The image recorded on the Film 10 is subsequently projected onto a planar screen 11 using the projection lens 8 of the projector, as shown in FIG. 2. However, such an image planarization process becomes a main cause of deterioration of the desired visual presence.
Empirically, viewers in specific seats of the theater experience a greater visual presence than viewers in other seats.
The reason is, as shown in FIG. 2, that the image incident at upper, lower, left, and right areas of the planar screen 11 is reflected at a reflection angle ∠B identical to an incidence angle ∠A. In this case, viewers can perceive the visual presence of the shooting angle, but only in a scope A of reverse angles to the reflection angle ∠B. For this reason, the range of a viewing field in which the visual presence of the original object can be felt is narrow, so that viewers cannot perceive a satisfactory visual presence.
As shown in FIG. 3a, the image incident into the upper, lower, left, and right portions of the screen is reflected at a reflection angle ∠B, so that viewers can perceive visual presence based on an image depth captured upon the shooting of the image, only within a scope A of reverse angles to the reflection angle ∠B. The scope A of reverse angles is so very narrow that it corresponds to two seats, as shown in FIG. 3b. 
In order to broaden the narrow field for the visual presence caused by the reflection angle ∠B, a method for maximizing scattering effects to obtain an increased uniformity of images may be used. In this case, however, it is necessary to reduce the reflectivity of the screen to 0.9-1.2%. For this reason, the screen is usable only in a dark room, and thus viewers do not see the desired image depth.
Gain is a unit representing the screen brightness and also represents the surface reflectivity of the planar screen 11. It is well known that 1 Gain equals a reflectivity of 1%.
According to the recent development of digital communications, sports broadcasts and live concerts, etc., are often relayed and televised in theaters. However, it is impossible to view these contents at a screen brightness adopted in typical theaters because the screen is too dark(the screen brightness is too low).
At the low screen brightness, it is impossible to obtain the satisfactory image depth and the desired color reproduction. For example, daylight scenes may look like night scenes. Due to a low contrast, there is little difference in color tone. For this reason, it is impossible to clearly display images.
In movie fields, many efforts to achieve an enhancement in brightness have been made in order to obtain the increased image depth. However, there is no way except intensifying the light source of the projector.
Particularly, when the distance between the screen and the seats is short, like in a small theater, the resolution of the screen is decreased so much that digital images with the visual presence cannot be applied to small theaters.
The Dolby system used as the theater sound facility is composed of a plurality of sound channels.
In the case of a Dolby system composed of 5.1 channels, two sets of speakers are arranged as front and rear stereo speakers, and a woofer for bass sound is arranged. Voices of actors and other sounds are outputted from central speakers 3.
The sound from the central speakers 3 is closely associated with the stereoscopic effect of images. In a conventional movie theater system illustrated in FIG. 4, central speakers 3 are located behind a planar screen 11. In this arrangement, a number of pores 9 are perforated through the planar screen 11 in order to forwardly transmit the sound from the central speakers 3 therethrough.
For this reason, the surface of the screen becomes rough, and the resolution and reflectivity of the screen are deteriorated, so that the brightness of the screen is lowered.
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a visual and audio system for a theater which is capable of extending the field in which the visual presence of an original image or object can be perceived, based on an image depth obtainable by a screen, to all seats in the theater, by increasing the brightness of the screen at least 5 times so as to implement projection of stereoscopic movies, by allowing viewers to view images at a bright place so as to show sports broadcasts at arena, live concerts relayed or televised on a screen at a concert, etc., by increasing surface resolution of the screen by at least 5 times so as to display clear images from a reduced distance for application to small-sized theaters, and by providing viewers with the effect that the sound from central speakers feels like it is coming directly from the screen.
In accordance with the present invention, this object is accomplished by providing a visual and audio system for a theater comprising: a spherical screen having a desired radius of curvature while having a surface reflectivity of 5-50%; at least one projector located at a focal point of the spherical screen, the projector comprising a film projector or a liquid crystal display projector; and seats arranged along a horizontal length of the spherical screen, whereby an image projected from the projector at the focal point of the spherical screen is reflected by the spherical screen in a horizontal direction, thereby causing a view field for viewing the image to be increased to a reverse angle range corresponding to the size of the spherical screen.